[llvm] [libsycl] Initial prefetch implementation for queue (PR #212104)

[via llvm-commits]

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@@ -307,7 +307,18 @@ void mock::MockLiboffload::initDefault() {
         EXPECT_NE(SrcDevice, nullptr);
         return OL_SUCCESS;
       });
-
+  ON_CALL(*this, olMemPrefetch)
+      .WillByDefault([this](ol_queue_handle_t Queue, size_t Count,
+                            const void **Mems, const size_t *Sizes,
+                            ol_mem_migration_flags_t Flags) -> ol_result_t {
+        EXPECT_NE(Queue, nullptr);
+        if (Count > 0) {
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Robertkq wrote:

This is correct, in runtime we actually always call with `Count == 1`, I've added more accurate `EXPECT`s now for the mock

https://github.com/llvm/llvm-project/pull/212104